Game of Thrones' Jon Snow actor Kit Harington reveals how his then-11-year-old co-star helped him with lines in a key scene. In season 6, Jon heads to Bear Island to recruit House Mormont for his army in preparation for the Battle of the Bastards to take back Winterfell. He is greeted by Lyanna Mormont, played by Bella Ramsey, who pledges House Mormont's forces to help Jon reclaim Winterfell from the ruthless Ramsay Bolton (Iwan Rheon) and his allies.